WASHINGTON (Reuters) - Transplanting genetically engineered
cells into the heart may help protect people who have survived
a heart attack from developing life-threatening heart rhythm
problems later on, scientists said on Wednesday.

The researchers showed the approach worked in mice,
protecting them from arrhythmia -- an irregularity in the
heart's natural rhythm -- after the animals' hearts were
damaged in a way similar to a heart attack.

They said they are hopeful the approach, with some
refinement, could help people who have heart attacks.

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"Approximately 15 percent of patients suffering from a
heart attack die within two to three years of sudden death due
to the development of ventricular arrhythmias," Bernd
Fleischmann of the University of Bonn in Germany, one of the
researchers, said by e-mail.

Fleischmann and his colleagues transplanted living mouse
embryonic heart cells into cardiac tissue of mice with heart
attack-like damage, making the animals resistant to later
arrhythmias, they said in a study in the journal Nature.

A protein known as connexin43 made by these transplanted
embryonic heart cells improved electrical connections to other
heart cells, the researchers said. The transplanted heart cells
became activated during normal heart contractions, they said.

The researchers noted that doctors could not use human
embryonic heart cells for transplantation in people for ethical
reasons. So they genetically engineered skeletal muscle cells
to make this protein.

'FUNCTIONAL CONNECTION'

By transplanting these cells into the mouse heart, they
said they achieved the same restorative results as with the
transplanted embryonic heart cells.

The type of cells they used are called myoblasts, which are
adult skeletal muscle stem cells.

"If we put in cells of a certain type, we really prove that
these cells, in fact, are activated by the surrounding heart
tissue during the normal heart beat. So this is really the
first demonstration that these cells can establish functional
connection and contract during normal heart function," Michael
Kotlikoff of Cornell University in Ithaca, New York, who worked
on the study, said in a telephone interview.

Kotlikoff said the study results suggest that doctors may
be able to take thigh muscle cells from a person who has had a
heart attack, genetically alter them to make connexin43, and
then put them into the person's heart to protect against
arrhythmia.

Because the cells are taken from the same person, the body
should not reject the transplanted cells, Kotlikoff said.

Doctors previously have tried to improve heart function by
implanting bone marrow cells or skeletal myoblasts into heart
tissue to help it recover from heart attack damage. Fleischmann
said those efforts were mainly for another purpose -- to
improve heart pump function.